Merging material slots?
If I understand it correctly, you have one object where different parts have different materials. But some parts have the same material split up in different material slots.
To merge them all into one material slot, change to Edit Mode first deselect all faces. Then choose the first &quot;wood panels&quot; material slot and click on Select under the material list. Now select the next &quot;wood panels&quot; slot and hit Select again. This adds the faces assigned to this material to the first selection. Repeat until all wooden parts are selected.
Now choose the wooden material slot you wish to keep and hit Assign. Now all faces are assigned to this one material. Back in Object Mode you can select a slot you don't need anymore and hit the minus button to delete it.